Au-RE-TiO2 nanocomposites: surface characteristics and photoactivity

Transkrypt

Physicochem. Probl. Miner. Process. 50(2), 2014, 551−561
Physicochemical Problems
of Mineral Processing
www.minproc.pwr.wroc.pl/journal/
ISSN 1643-1049 (print)
ISSN 2084-4735 (online)
Received August 19, 2013; reviewed; accepted November 06, 2013
Au-RE-TiO2 NANOCOMPOSITES. SURFACE
CHARACTERISTICS AND PHOTOACTIVITY
Anna KRUKOWSKA*,**, Joanna RESZCZYNSKA*, Adriana ZALESKA*,**
*
Department of Chemical Technology, Gdansk University of Technology, 80-233 Gdansk, Poland
Department of Environmental Engineering, University of Gdansk, 80-952 Gdansk, Poland,
[email protected]
**
Abstract: Photocatalysts based on TiO2 co-doped with rare earth metal (RE) and gold nanoparticles have
been prepared using a sol-gel method and followed by gold reduction. Specific surface areas of the
modified photocatalysts were calculated by the Brunauer-Emmett-Teller method (BET). Diffuse
reflectance spectra of the obtained photocatalysts were recorded with a UV-Vis spectrophotometer (DRS
UV-Vis). The influence of the type of rare earth metal on photoactivity of Au-RE-TiO2 nanocomposites
in model reaction manifested by toluene photodegradation in a gas phase was investigated. The obtained
results showed that photodegradation of toluene in the gas phase is possible over Au-RE-TiO2 irradiated
by UV or Vis light. The Au-RE-TiO2 photocatalysts relative to undoped TiO2, did not caused an increase
of toluene degradation in the air under visible light. The samples doped with Er3+ or Pr3+ presented the
highest activity in solar light among of Au-RE-TiO2. It was observed that both metal dopants affected the
surface area of TiO2. The Au-RE-TiO2 photocatalysts relative to undoped TiO2 exhibited the absorption
properties under Vis light.
Keywords: photocatalysis, modified TiO2, rare earth metal, Au nanoparticles, toluene degradation
Introduction
Advanced oxidation with the aid of sunlight sensitive photocatalysts may prove to be a
solution to environment pollution (Fujishima et al., 2000). Photochemical reactions
catalyzed by TiO2 were investigated in the degradation of dyes, hazardous substances
in contaminated air and wastewater streams (Ibhadon and Fitzpatrick, 2013). Titanium
dioxide is one of the most promising materials in heterogeneous photocatalytic
oxidation due to its effectiveness, chemical stability, cheapness and availability. It also
exhibits strong purifying power (Zaleska et al., 2007). Although TiO2 has a large band
gap of 3.3 eV in anatase crystalline phase, it can be activated only by UV light and
from 3% to 5% of Vis light, limiting utilization of sunlight as the source in
http://dx.doi.org/10.5277/ppmp140211
552
A. Krukowska, J. Reszczynska, A. Zaleska
photocatalytic reactions. The development of modified TiO2 photocatalysts should
exhibit high reactivity under Vis light in the main part of the solar spectrum (Parida et
al., 2008). Modified TiO2 photocatalysts with enhanced activity under sunlight can be
prepared by doping metal elements such as rare earth metal (Parida and Sahu, 2008) or
noble metal (Boyd et al., 2005; Zielinska-Jurek et al., 2011).
If a metal or non-metal is used as a doping agent for TiO2, these energy levels can
be incorporated into the band gap of TiO2. A new energy levels can either accept
electrons from the valence band or donate electrons to the conduction band. Owing to
less energy separation between the new energy levels and the valence band or
conduction band, visible light becomes energetic enough to facilitate the above
mentioned electron transitions (Bingham and Daoud, 2010). Reducing the size of the
band gap by introducing energy levels between the conduction band and valence band
allowed TiO2 to be active under visible light. This is the main idea of metal and nonmetal doping.
Doping can be achieved through the sol-gel process, hydrothermal synthesis,
electrospinning and magnetron sputtering (Diamandesceu et al., 2008; Yang et al.,
2011). The sol-gel is one of the wet chemistry method used in non-metal or metal
doping TiO2. The wet chemistry methods usually involve hydrolysis of titanium
precursor in a mixture of water and other reagents followed by heating (Chen and
Mao, 2007). The benefits of sol-gel method are compositional control, homogeneity
on the molecular level due to mixing liquid precursors and low preparation
temperature. However, the influence of organic traces on the optical quality of the
material might be noticeable. Furthermore, the traditional sol-gel techniques might not
be applicable to complex-shaped surfaces (Kanarjov et al., 2008). It can be inferred
that the sol-gel method conditions can allow for either lanthanide ions to form oxides
dispersed on the exterior of the semiconductor or incorporation in the titania matrix
(Su et al., 2004).
Noble metal nanoparticles (gold, silver, platinum, et cetera) were used to enhance
photocatalytic activity of TiO2 (Chuang and Chen, 2009). Gold nanoparticles possess
ability to absorb visible light, due to a localized surface plasmon resonance (LSPR).
The samples of Au-TiO2 nanoparticles showed plasmon absorption bands at about
550 nm. The activity of Au-TiO2 photocatalysis depends on the preparation method
and on the size and shape of gold nanoparticles (Kowalska et al., 2010). The gold
nanoparticles less than 5 nm in size are the most active catalysts (Haruta et al., 1993).
A rare earth metal (RE) was doped TiO2 in an attempt to achieve visible light
photocatalysis. The rare earth metal established complexation with RE-O-Ti bond on
the inner sphere surface, which inhibited the transformation from anatase to rutile (Liu
et al., 2012). The best photocatalytic properties in visible light were the TiO2 doped
with Nd3+ (Stengl et al, 2009), and Gd3+ (Xu et al., 2002) due to their the lowest band
gap, particle size, highest surface area and pore volume. The RE-doped TiO2
nanomaterials usually showed large surface area and high porosity. A larger surface
area provided more surface active sites for the adsorption of reactants molecules,
Au-RE-TiO2 nanocomposites. Surface characteristics and photoactivity
553
which make the photocatalytic process more efficient (Hassan et al., 2012). Co-doping
TiO2 with different elements showed different absorption and photocatalytic properties
to those doped individually (He et al., 2008).
In this paper, we present a novel approach for obtaining RE-doped TiO2 loaded
with Au nanoparticles. The influence of rare metal type (Ho, Nd, Er, Eu and Pr) on
Au-TiO2 surface properties and photoactivity in the gas phase reaction was
investigated.
Experimental
Materials and instruments
Titanium isopropoxide (97%, Sigma Aldrich) with acetic acid (99 %, POCH S.A.) and
ethanol (96 %, POCH S.A.) were used for the preparation of TiO2 nanoparticles. The
precursors of rare earth metal as salts: Ho(NO3)3·5H2O, Nd(NO3)3·6H2O,
Er(NO3)3·5H2O, Eu(NO3)3·5H2O and Pr(NO3)3·6H2O were provided from Sigma
Aldrich. Hydrogen tetrachloroaurate (III) (99%, Sigma Aldrich) was used as the
precursor for preparation gold nanoparticles. Ammonium hydroxide (25%, Sigma
Aldrich) was exploited to adjust the pH above 8.5 of the solution. Sodium borohydride
(99%, Sigma Aldrich) was used to reduce the gold nanoparticles. Deionized water was
exploited for all the reactions and treatment processes.
Specific surface areas of the modified photocatalysts were determined by the
Brunauer-Emmett-Teller method (BET). Nitrogen adsorption-desorption isotherms
were measured at liquid nitrogen temperature (77 K) on a Micromeritics Gemini V,
model 2365 PC. Prior to analysis, the samples were degassed at 200 ºC for 2 h.
Diffuse reflectance spectra (DRS) of the obtained photocatalysts were
characterized using a UV-Vis spectrophotometer Thermo Evolution Nicolet,
model 220 equipped with ISA 220 integrating sphere accessory. The UV-Vis DRS
spectra were recorded in the range of 300–900 nm using sulfate barium as the
reference standard.
Prepartion of Au-RE-TiO2 photocatalysts
The preparation of Au-RE-TiO2 photocatalysts is presented in a block diagram in
Fig. 1. In the first step RE-modified TiO2 was prepared using the sol-gel method. The
sample of 15 cm3 titanium isopropoxide was added to the mixture of 3 cm3 acetic acid
and 60 cm3 ethanol. The sol was stirred for 10 min. Then rare earth nitrate was
dissolved in 2 cm3 water, added dropwise to the solution, and stirred for 2 h. The gel
was dried at 80 ºC for 24 h to remove the solvents and then calcined in air at 400 ºC
for 4 h at the heating rate of 2 ºC/min in an oven. Calcination is used to transform
TiO2 amorphous form to anatase or rutile crystal structure. Enhancing the
photocatalytic activity of TiO2 can be achieved by calcination at temperature of
400 °C allowing TiO2 to receive anatase crystal structure. The temperature of anatase
554
TIP
CH3COOH
C2H5OH
MIXING
25oC
WATER SOLUTION RE(NO3)3
MIXING
25oC
DRYING
80oC
WATER, SOLVENT
CALCINATION
400oC
WATER, SOLVENT,
POLLUTION
HAuCl4
MIXING
25oC
NH4OH
ADJUSTMENT OF pH
NaBH4
REDUCTION OF GOLD
H2O
WASH IT OUT
WASHINGS
DRYING
80oC
Au-RE-TiO2 PHOTOCATALYSTS
Fig. 1. Block diagram of preparation of Au-RE-TiO2 photocatalysts
to rutile transformation is estimated to be over 500 ºC (Chen and Mao, 2007). The
obtained sample was milled into powder. In the second step Au-modified RE-TiO2
555
was prepared by the reduction method. Hydrogen tetrachloroaurate (III) as the gold
precursor was added to water suspension of RE-TiO2 powder. The pH 8.5 of
dispersion was adjusted with 25% ammonium hydroxide. The gold nanoparticles were
reduced by sodium borohydride. The solution turned from transparent to violet color
due to reduction of Au ions. The gel was dried again at 80 ºC for 12 h. In modified
TiO2 the concentration of rare earth metal was permanently 0.5 mol.% and the
concentration of gold nanoparticles were 1 or 2 mol % related to the concentration of
TIP. Pure TiO2 and Au-TiO2 were prepared in the same way.
Measurements of photocatalytic activity
The photocatalytic activity of Au-RE-TiO2 powders in visible light was estimated by a
model photodegradation toluene in the air. Photochemical reactions were carried out
in a custom-made photoreactor with replacements, two sets of 25 LED lamps in range
UV light (wavelength 375 nm) or Vis light (wavelength 415 nm). Gases from the
reactor were analyzed using an on-line gas chromatography, PerkinElmer, model
Clarsus 500 (Nischk et al., 2014).
Results and discussion
Table 1 summarizes the measured BET surface area, total pore volume, pore diameter
and photocatalytic activity results for TiO2 co-doped with selected rare earth metal
(holmium, neodymium, erbium, europium or praseodymium) and gold nanoparticles.
The TiO2 as a reference material has the lowest BET surface area and pore volume of
about 115 m2/g and 0.1 cm3/g. The 2 % Au-0.5 % Pr-TiO2 and 2 % Au-0.5 % Eu-TiO2
have the highest surface area equal to about 139 m2/g. For other Au-RE-TiO2 samples
containing from 1 to 2 mol % of gold and 0.5% rare earth metal the surface areas
varied from 134 to 139 m2/g. The 2% Au-0.5% Nd-TiO2 had the lowest pore diameter
of about 1.91 nm. The pure TiO2 showed well-crystallized anatase structure. Despite
having a higher BET surface area, Au-RE-TiO2 have not caused an increase
photocatalytic activity relative to undoped TiO2. It could be considered that pore
accessibility of TiO2 is constrained by rare earth metals. On the other hand it might be
a consequence of remaining carbon deposits on the nanocomposites, which came from
titanium isopropoxide. Xu et al. (2002) reported that the rare earth metal salts can be
changed into rare earth oxides during the calcinations process. Therefore, it can be
inferred that the rare earth ions were dispersed on the surface of TiO2 in the form of
small clusters, which inhibit TiO2 amorphous structure transform to the anatase crystal
structure.
The light absorption properties of prepared Au-RE-TiO2 photocatalysts, DRS UVVis absorption spectra in the range of 300-900 nm were investigated and the results
are shown in Fig. 2. The spectrum of DRS UV-Vis showed that the undoped TiO2
decreased by light reflection at a wavelength of about 380 nm, what proved that it
556
Table 1 Surface properties and photocatalytic activity of Au-RE-TiO2 samples
Photocatalysts type
2 % Au-0.5 % Ho-TiO2
2 % Au-0.5 % Nd-TiO2
2 % Au-0.5 % Er-TiO2
2 % Au-0.5 % Eu-TiO2
2 % Au-0.5 % Pr-TiO2
1 % Au-0.5 % Pr-TiO2
2 % Au-TiO2
TiO2
SBET
(m2/g)
Pore volume
(cm3/g)
Pore diameter
(4V/SBET) (nm)
135
137
137
139
139
134
122
115
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
1.92
1.91
1.95
1.95
1.95
1.93
1.95
1.95
Photocatalytic activity (%)
UV light
Vis light
31
38
63
52
44
38
39
100
46
47
99
76
99
88
97
100
absorbs only UV light. Other photocatalysts Au-RE-TiO2 had the highest absorption
properties under Vis light in typical absorption peaks located at about 550 nm, which
is characteristic for gold plasmon. The maximum absorbance under Vis light exhibited
2% Au-0.5% Pr-TiO2. It proved that a redshift in the band gap transition of TiO2 is
due to the presence of the rare earth metal and gold. It could be achieved by a charge
transfer transition between the lanthanide f electrons and the conduction or valence
band of the TiO2 (Hassan et al., 2012).
2 % Au-0.5 % Pr-TiO2
2 % Au-0.5 % Nd-TiO2
2 % Au-0.5 % Ho-TiO2
Absorbance
2 % Au-0.5 % Eu-TiO2
2 % Au-0.5 % Er-TiO2
2 % Au-TiO2
1 % Au-0.5 % Pr-TiO2
pure TiO2
300
400
500
600
700
800
900
Wavelength (nm)
Fig. 2. Diffuse reflectance spectroscopy spectra of Au-RE-TiO2 photocatalysts
The photocatalytic activity of Au-RE-TiO2 photocatalysts was checked by
measuring the decomposition of toluene in the air under UV or Vis light. The
efficiency of toluene photodegradation after 30 min of exposure to visible light in the
presence of Au-RE-TiO2 photocatalysts is reported in Table 1 (efficiency of
photodegradation toluene in one cycle of photocatalytic reaction) and Figs. 3 and 4
557
(efficiency of toluene photodegradation under UV or Vis light in four subsequent
cycles). All photocatalysts based on TiO2 co-doped with the rare earth metal and gold
nanoparticles showed lower photocatalytic activity than pure TiO2. The highest
activity in solar light from among Au-RE-TiO2 presented the sample doped with Er3+
or Pr3+ as the rare earth metal, which received about 50% efficiency degradation of
toluene. It indicates that the presence of 2% Au-0.5% Er-TiO2 and 2% Au-0.5% Pr2%Au-0.5%Nd-TiO2
2%Au-0.5%Ho-TiO2
100
Toluene concentration, c/co (%)
100
80
60
40
20
80
60
40
20
0
0
0
5
10
15
20
25
0
30
2%Au-0.5%Er-TiO2
10
15
20
25
30
2%Au-0.5%Eu-TiO2
100
100
80
60
40
20
80
60
40
100
20
2%Au-0.5%Er-TiO2
5
Time (min)
Time (min)
2%Au-0.5%Er-TiO2
1st cycle (Vis)
2nd cycle (Vis)
01st cycle (Vis)
0100
3rd cycle (Vis)
0
5
10
15
20
25
30
0
5
10
15
20 8025
30
2nd
cycle
(Vis)
2%Au-0.5%Er-TiO2
60
Time (min)4th cycle (Vis)
Time (min)
1st cycle (Vis)
1st cycle (UV)
3rd cycle (Vis)
80
2nd60cycle (Vis)
4th cycle (Vis)
2nd cycle (UV)
1st cycle (Vis)
3rd cycle (Vis)
1st40cycle (UV)
3rd cycle (UV)
4th cycle (Vis)
2nd
2nd cycle (UV)
60 cycle (Vis)
4th cycle (UV)
1st 40
cycle (UV)
3rd cycle (Vis)
3rd cycle (UV)
20 in four subsequent cycles
Fig. 3. Efficiency of 2nd
toluene
removal
cycle
(UV)from gas phase
4th cycle
(UV)
4th cycle (Vis)
in the presence of Au-RE-TiO2 under UV or Vis irradiation
40
3rd20
cycle (UV)
1st cycle (UV)
4th cycle (UV)
2nd cycle (UV)
0
3rd
cycle
(UV)
05115
020
25
30
20
0
Time (min)
4th cycle (UV)
100
2%Au-0.5%Er-TiO2
05115
020
25
30
0
Time (min)
80
558
2%Au-0.5%Pr-TiO2
1%Au-0.5%Pr-TiO2
100
100
80
60
40
20
0
80
60
40
20
0
0
5
10
15
20
25
0
30
Time (min)
10
15
20
25
30
Time (min)
2%Au-TiO2
pure TiO2
80
60
40
20
100
100
80
60
40
100
2%Au-0.5%Er-TiO2
2%Au-0.5%Er-TiO2
20
100
5
05115
020
25
30
me (min)
1st cycle (Vis)
2nd cycle (Vis)
2%Au-0.5%Er-TiO2
0100
0 cycle (Vis)
3rd cycle (Vis)
1st
0
0
5
5
10
10
15
15
20 80 25
20
25
30
30
2nd
cycle
(Vis)
60
2%Au-0.5%Er-TiO2
Time (min)
Time (min)4th cycle (Vis)
1st cycle (Vis)
3rd cycle (Vis)
1st cycle (UV)
80
2nd60cycle (Vis)
4th cycle (Vis)
2nd cycle (UV)
40cycle (UV)
1st cycle (Vis)
3rd cycle (Vis)
1st
3rd cycle (UV)
2nd
4th cycle (Vis)
60cycle (Vis)
2nd cycle (UV)
4th cycle (UV)
1st40cycle (UV)
3rd cycle (Vis)
3rd cycle (UV)
20 in four subsequent cycles
Fig. (Vis)
4. Efficiency of 2nd
toluene
removal
cycle
(UV)from gas phase
4th cycle
4th cycle (UV)
in the presence of Au-Pr-TiO2, Au-TiO2 and pure TiO2 under UV or Vis irradiation
40
3rd cycle (UV)
1st cycle (UV)
20
4th cycle (UV)
2nd cycle (UV)
0
TiO2 3rd
were
close
for
UV
light
activation to undoped
TiO2, where the maximum
cycle (UV)
05115
020
25
30
20
efficiency
of
toluene
degradation
was
almost
100%.
Other
photocatalysts Au-RE-TiO2
4th cycle (UV)
Time (min)
0
80
3+
based on TiO2 co-doped with Ho3+
,020
Ne
or Eu3+ and gold nanoparticles showed lower
05115
25
30
Time (min) to unmodified TiO . As can be seen in the
activity in
0 UV and Vis light compared
2
0
5
1
15
0
20
25
30
investigations that toluene photodegradation efficiency did not decrease in fourth
Time (min)
559
cycles photocatalytic reactions. The photocatalytic activity of Au-RE-TiO2 under UV
light is always higher than under Vis light due to physico-chemical properties of TiO2
and energy of light. The curtailment amount of gold from 2% to 1% wt % in the
photocatalysts Au-Pr-TiO2 under UV light causes reduction in toluene
photodegradation activity. To the best of our knowledge no one has previously
reported photocatalyst activity of Au-RE-TiO2 powders and it cannot be compared to
results from literature data. Xu at el. (2002) reported that results of photodegradation
conversion of nitrite over RE-doped TiO2 (RE: Er3+, Pr3+, La3+, Nd3+, Ga3+) and UVVis light show higher photoreactivity than pure TiO2. Zielinska-Jurek et al. (2011)
investigated impacts in decomposition of aqueous phenol solution by Au-TiO2 and
Au/Ag-TiO2 powders under Vis light. The Au/Ag-TiO2 samples show higher
photocatalytic activity than Au-TiO2.
Conclusion
Our preliminary results showed that photodegradation of toluene in the air over AuRE-TiO2 using light emitting diodes is possible. However, it was found that co-doping
of TiO2 with the rare earth metal and gold nanoparticles inhibited photoactivity both
under UV and Vis irradiation compared to pure TiO2. The highest activity under
visible light from among Au-RE-TiO2 was observed for the sample doped with Er3+ or
Pr3+. Reducing the concentration of gold precursor from 2 to 1 mol.% during
synthesis, resulted in decrease of photocatalytic activity. It was observed that TiO2
surface modification with the rare earth metal and gold nanoparticles caused decrease
of the surface area of modified TiO2 powders. Since plasmon band near 550 nm
typical for gold nanoparticles was observed, the sol-gel preparation method followed
by chemical reduction of gold ions did not enhance photoactivity under visible light.
On the basis of the analysis, it is suggested that more detailed studies into the
mechanism of Au-RE-TiO2 photoexcitation is required.
Acknowledgments
This research was financially supported by Polish National Science Center
(grant No. 2011/01/N/ST5/05537).
References
BINGHAM S., DAOUD W.A., 2011, Recent advances in making nano-sized TiO2 visible-light active
through rare-earth metal doping, J. Mater. Chem. 21, 2041–2050.
BOYD, D., GOLUNSKI, S., HEARNE, G.R., MAGADZU, T., MALLICK, K., RAPHULU, M.C.,
VENUGOPAL, A., SCURRELL, M.S., Reductive routes to stabilized nanogold and relation to
catalysis by supported gold, Appl. Catal. A 292, 76–81.
CHEN X., MAO S.S., 2007, Titanium dioxide nanomaterials: Synthesis, properties, modifications and
applications, Chem. Rev. 107, 2891–2959.
560
CHUANG H.,CHEN D., 2009, Fabrication and photocatalytic activities in visible and UV light regions
of Ag-TiO2 and NiAg-TiO2 nanoparticles, Nanotechnology 20, 105704.
DIAMANDESCU L., VASILIU F., TARABASANU-MIHAILA D., FEDER M., VLAICU A.M.,
TEODORESCU C.M., MACOVEI D., ENCULESCU I., PARVULESCU V., VASILE E., 2008,
Structural and photocatalytic properties of iron- and europium-doped TiO2 nanoparticles obtained
under hydrothermal conditions, Mater. Chem. Phys. 112, 146–152.
FUJISHIMA A., RAO T.N., TRYK D.A., 2000, Titanium dioxide photocatalysis, J. Photochem.
Photobiol., C: Photochem. Rev. 1, 1–21.
HARUTA M., TSUBOTA S., KOBAYASHI T., KAGEYAMA H., GENET M.J., DELMON B., Lowtemperature oxidation of CO over gold supported on TiO2, α-Fe2O3, and Co3O4, 1993,
J. Catal. 144, 175–192.
HASSAN M.S., AMNA T., YANG O.-B., KIM H.-C., KHIL M.-S., 2012, TiO2 nanofibers doped with
rare earth elements and their photocatalytic activity, Ceram. Int. 38, 5925–5930.
HE Y.Q., XU X., SONG S., XIE L., TU J.J., CHEN J.M., YAN B., 2008, A visible light-driven titanium
dioxide photocatalyst codoped with lanthanum and iodine: an application in the degradation of
oxalic acid, J. Phys. Chem. C 112, 16431–16437.
IBHADON A.O., FITZPATRICK P., 2013, Heterogeneous photocatalysis: recent advances and
applications, Catalysts 3, 189–218.
KANARJOV P., REEDO V., OJA ACIK I., MATISEN L., VOROBJOV A., KIISK V., KRUNKS M.,
SILDOS I., 2008, Luminescent materials based on thin metal oxide films doped with rare earth
ions, Phys. Solid State 50, 1727–1730.
KOWALSKA E., MAHANEY O.O., ABE R., OHTANI B., 2010, Visible-light-induced photocatalysis
through surface plasmon excitation of gold on titania surfaces Phys. Chem. Chem. Phys. 12, 2344–
2355.
LIU H., YU L., CHEN W., LI Y., 2012, The progress of TiO2 nanocrystals doped with rare earth ions
J. Nano Mat. 2012, art. no. 235879.
NISCHK M., MAZIERSKI P., GAZDA M., ZALESKA A., 2014, Ordered TiO2 nanotubes: The effect of
preparation parameters on the photocatalytic activity in air purification process, App. Catal. BEnviron. 144, 674–685.
PARIDA K.M., MOHAPATRA P., MOMA J., JORDAAN W.A., SCURRELL M.S., 2008, Effects of
preparation methods on gold/titania catalysts for CO oxidation, J. Mol. Catal. A: Chem. 288, 125–
130.
PARIDA K.M., SAHU N., 2008, Visible light induced photocatalytic activity of rare earth titania
nanocomposites, Appl. Catal. A 287, 151–158.
SU C., HONG B.Y., TSENG C.M., 2004, Sol-gel preparation and photocatalysis of titanium dioxide,
Catal. Today 96, 119–126.
STENGL V., BAKARDJIEVA S., MURAFA N., 2009, Preparation and photocatalytic activity of rare
earth doped TiO2 nanoparticles, Mater. Chem. Phys. 114, 217–226.
XU A.W., GAO Y., LIU H.Q., 2002, The preparation, characterization, and their photocatalytic
activities of rare-earth-doped TiO2 nanoparticles, J. Catal. 207, 151–157.
YANG Z., ZHU K., SONG Z., ZHOU D., YIN Z., QIU J., 2011, Preparation and upconversion emission
properties of TiO2: Yb, Er inverse opals, Sol. Stat. Comm. 151, 364–367.
561
ZALESKA A., SOBCZAK J.W., GRABOWSKA E., HUPKA J., 2007, Preparation and photocatalytic
activity of boron-modified TiO2 under UV and visible light, Appl. Catal. B 78, 92–100.
ZIELINSKA-JUREK A., KOWALSKA E., SOBCZAK J., LISOWSKI W., OHATANI B., ZALESKA
A., 2011, Preparation and characterization of monometallic (Au) and bimetallic (Ag/Au) modifiedtitania photocatalysts activated by visible light, Appl. Catal. B 101, 504–514.
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Au-RE-TiO2 nanocomposites: surface characteristics and photoactivity

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